Whether you’re a fan of Roger Ebert’s film criticism or not (I am, his work is erudite, enthusiastic and accessible) you’d have to have a heart made of stone not to be moved by this wonderful documentary. Made when Ebert was suffering through a variety of, ultimately failed, medical treatments this film transcends its premise (to show a warts and all review of his career) to become a beautiful essay in the power of love and devotion. Although the first half covers Ebert’s career with a welcome honesty, particularly his love/hate relationship with Gene Siskel, and his break through into becoming a cultural commentator as much as a critic, it’s the final third of the film where it takes off. A documentary about a man, becomes a love story between Ebert and his wife Chaz. Chaz’s devotion is incredible, as is Ebert’s humour and dedication to writing that helps sustain him even when his voice is gone. It is one of life’s cruel ironies that such a passionate speaker should be silenced, but as long as his fingers kept moving, he kept writing.

It’s no spoiler to reveal how the film ends, with Ebert’s passing. The real surprises in this film come from the warmth he inspired, and his willingness to embrace film from all areas. Oh for a popular film show that took criticism and debate seriously as he and Siskel did. Kudos to, to Steve James. Shaping a documentary must be a nightmare, without the reliance on a pre-defined structure. He remains present but unobtrusive in his own film, allowing the subjects to speak for themselves.

We’re living in a really good age for theatrically released documentaries. What’s remarkable is the diversity of tone and angle taken by the filmmakers: some base their appeal on the documentary maker (a la Morgon Spurlock), some let the subject speak for themselves (like Nick Broomfield). Alex Gibney sits in between. He gives The Armstrong Lie a personal edge, but one that elaborates on Armstrong’s own appeal. Just like everyone else Gibney was seduced by Armstrong, and to his credit he admits that.

Begun in 2009 when Armstrong was attempting a comeback at the Tour de France the film went on hiatus when Armstrong’s doping broke in the press. Picking up in 2013 Gibney interviews Armstrong about the lying and cheating that forged his career. It’s a very well structured film, cutting back and forth between different parts of Armstrong’s career, exposing his domineering behaviour and casual bullying, and the lengths to which the elite cyclists go to gain a competitive edge (including blood transfusions). It’s a terrific portrait of a self-deluding narcissist and even by the end of the film, Armstrong still can’t quite be honest with himself, or us.

In a time when celebrities are being exposed for far worse than Armstrong’s deception, The Armstrong Lie provides a timely reminder of how investing heroes with blind faith can come back to haunt us.